Various forms of workpiece stops heretofore have been provided for use in conjunction with machine tool spindles of lathes, screw machines, and surface grinders, etc., but most of these machine tool workpiece stops are constructed in a manner whereby they are adapted for use in conjunction with a specific machine tool and may not be readily transferred from one form of machine tool to another. Examples of various forms of workpiece stops and other structures including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 313,562, 866.788, 2,189,968, 2,361,085, 2,423,551, 2,450,004, 3,779,566, and 3,876,214.